1. Field of the Invention
The invention relates in general to a touch device, and more particularly to an optical touch apparatus and an optical touch method.
2. Description of the Related Art
In a conventional optical touch system without reflective borders, an optical sensor is fixed on a touch panel. The optical sensor senses a light pen to output a sensing signal. The light pen reflects light that is emitted from a light emitting diode (LED) of the optical sensor. The conventional optical touch system determines whether the light pen contacts the touch panel according to a fixed threshold value. However, as the distance between the light pen and the optical sensor varies, the magnitude of the sensing signal also varies. If the fixed threshold value is too low, the calculation of touch point may be started too early when the light pen is near the optical sensor. Conversely, if the fixed threshold value is too high, the touch signal may not be detected when the light pen is far away from the sensor.